A term popular in jail. A courteous thing to do when you have a cellmate and are in the small confines of a jail cell. A method you perform when in the jail cell to eliminate the smell of your bowel movement. Usually executed at the point of release from the anus and before it hits the water. The suction of downforce of the flush eliminates the gases as well as the odor of the loaf.
"Yo, do a courtesy flush bro, that shit smells dude."